The present invention relates to aluminum components for a substrate processing chamber and methods of manufacturing the same.
In the processing of a substrate in a substrate processing chamber, as in the manufacture of integrated circuits and displays, the substrate is typically exposed to energized gases that are capable of, for example, etching or depositing material on the substrate. The energized gases can also be provided to clean surfaces of the chamber. However, the energized gases can often comprise corrosive halogen-containing gases and other energized species that can corrode components of the chamber, such as enclosure walls of the chamber. For example, chamber components made of aluminum can chemically react with energized halogen-containing gases to form AlCl3 or AlF3, thereby corroding the components. The corroded portions of the components can flake off and contaminate the substrate, which reduces the substrate yield. Thus, the corroded components must often be replaced or removed from the chamber and cleaned, resulting in undesirable chamber downtime.
The corrosion resistance of a chamber component can be improved by forming a coating of a corrosion resistant material over surfaces of the component that are susceptible to corrosion, such as surfaces that would otherwise be exposed to the energized gas. For example, a coating of aluminum oxide can be formed on surfaces of an aluminum component to form a coating that exhibits improved corrosion resistance. One method to form an aluminum oxide coating on an aluminum component is to anodize the aluminum component in an electrolytic cell. However, there are problems with such an anodized aluminum oxide coating. For example, anodized aluminum oxide coatings often contain surface features such as pores, cracks, indentures, and other penetrating surface features that limit the effectiveness of the coating to protect the underlying aluminum component. For example, surface features that penetrate deep into the protective coating allow corrosive gases relatively closer access to the underlying component material having the coating to corrode from within, which can lead to flaking off of the coating from the component.
One way to improve the performance of an anodized aluminum oxide coating is disclosed in U.S. Pat. No. 6,565,984 to Wu et al. and commonly assigned to Applied Materials Inc., issued May 20, 2003, which is herein incorporated by reference in its entirety. Wu et al. discloses an aluminum alloy article in which defects on the upper surface of an anodized aluminum oxide layer are controlled by controlling particulate inclusions at the surface of the aluminum article on which the anodized layer is formed. Particulate inclusions at the surface of the aluminum article are controlled by controlling the concentration of impurities in the comprising aluminum alloy. However, this approach is also deficient in some aspects. For example, an aluminum alloy with controlled impurity levels may be costly to produce. Additionally, this approach only accounts for anodized aluminum oxide surface defects caused by particulate inclusions at the surface of the underlying aluminum article. There may be other causes for defects on the surface of the anodized aluminum oxide layer. For example, the anodized aluminum oxide layer may inherently have a porosity that is independent of particulate inclusions on the surface of the aluminum article. Additionally, there may be cracks and other surface features caused by inherent imperfections in the anodization process.
Thus, there is a need for aluminum components that exhibit improved corrosion resistance to energized gases. There is also a need for aluminum components having an aluminum oxide coating that exhibits improved corrosion resistance and is less susceptible to flaking off the aluminum component.